[MDEP-832] - Remove commons-collections-4

pom.xml

@@ -222,12 +222,6 @@ under the License.
       <version>3.12.0</version>
     </dependency>
 
-    <dependency>
-      <groupId>org.apache.commons</groupId>
-      <artifactId>commons-collections4</artifactId>
-      <version>4.2</version>
-    </dependency>
-
     <!-- dependencies to annotations -->
     <dependency>
       <groupId>org.apache.maven.plugin-tools</groupId>
@@ -273,6 +267,12 @@ under the License.
       <version>4.13.2</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.assertj</groupId>
+      <artifactId>assertj-core</artifactId>
+      <version>3.23.1</version>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.apache.maven.plugin-testing</groupId>
       <artifactId>maven-plugin-testing-harness</artifactId>

src/main/java/org/apache/maven/plugins/dependency/analyze/AnalyzeDuplicateMojo.java

@@ -21,14 +21,13 @@
 
 import java.io.IOException;
 import java.io.Reader;
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.stream.Collectors;
 
-import org.apache.commons.collections4.CollectionUtils;
 import org.apache.maven.model.Dependency;
 import org.apache.maven.model.Model;
 import org.apache.maven.model.io.xpp3.MavenXpp3Reader;
@@ -151,15 +150,9 @@ private void createMessage( Set<String> duplicateDependencies, StringBuilder sb,
 
     private Set<String> findDuplicateDependencies( List<Dependency> modelDependencies )
     {
-        List<String> modelDependencies2 = new ArrayList<>();
-        for ( Dependency dep : modelDependencies )
-        {
-            modelDependencies2.add( dep.getManagementKey() );
-        }
-
-        // @formatter:off
+        List<String> modelDependencies2 =
+                modelDependencies.stream().map( Dependency::getManagementKey ).collect( Collectors.toList() );
         return new LinkedHashSet<>(
-                CollectionUtils.disjunction( modelDependencies2, new LinkedHashSet<>( modelDependencies2 ) ) );
-        // @formatter:on
+                Util.symmetricDifference( modelDependencies2, new LinkedHashSet<>( modelDependencies2 ) ) );
     }
 }

src/main/java/org/apache/maven/plugins/dependency/analyze/Util.java

@@ -0,0 +1,58 @@
+package org.apache.maven.plugins.dependency.analyze;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+import static java.util.function.Function.identity;
+import static java.util.stream.Collectors.collectingAndThen;
+import static java.util.stream.Collectors.groupingBy;
+import static java.util.stream.Collectors.summingInt;
+import static java.util.stream.Collectors.toList;
+
+class Util
+{
+
+    static <O> Collection<O> symmetricDifference( Collection<O> elementsOne,
+                                                  Collection<O> elementsTwo )
+    {
+        Set<O> hashSet = new HashSet<>( elementsOne );
+        hashSet.addAll( elementsTwo );
+
+        Map<O, Integer> cardinalityOne =
+                elementsOne.stream().collect( groupingBy( identity(), summingInt( e -> 1 ) ) );
+        Map<O, Integer> cardinalityTwo =
+                elementsTwo.stream().collect( groupingBy( identity(), summingInt( e -> 1 ) ) );
+
+        return hashSet.stream().flatMap( item ->
+        {
+            int cardOne = cardinalityOne.getOrDefault( item, 0 );
+            int cardTwo = cardinalityTwo.getOrDefault( item, 0 );
+            int max = Math.max( cardOne, cardTwo );
+            int min = Math.min( cardOne, cardTwo );
+            return Collections.nCopies( max - min, item ).stream();
+        } ).collect( collectingAndThen( toList(), Collections::unmodifiableList ) );
+    }
+
+}

src/test/java/org/apache/maven/plugins/dependency/analyze/UtilTest.java

@@ -0,0 +1,113 @@
+package org.apache.maven.plugins.dependency.analyze;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class UtilTest
+{
+
+    @Test
+    public void two_lists_one_with_duplicates()
+    {
+        List<String> s1 = new ArrayList<>();
+        s1.add( "1" );
+        s1.add( "2" );
+        s1.add( "2" );
+        s1.add( "3" );
+        List<String> s2 = new ArrayList<>();
+        s2.add( "3" );
+        s2.add( "4" );
+        Collection<String> result = Util.symmetricDifference( s1, s2 );
+
+        assertThat( result ).containsExactly( "1", "2", "2", "4" );
+    }
+
+    @Test
+    public void two_different_sets_with_commons_elements()
+    {
+        Set<String> s1 = new HashSet<>();
+        s1.add( "1" );
+        s1.add( "2" );
+        s1.add( "3" );
+        s1.add( "4" );
+        s1.add( "5" );
+        Set<String> s2 = new HashSet<>();
+        s2.add( "2" );
+        s2.add( "4" );
+        s2.add( "6" );
+        Collection<String> result = Util.symmetricDifference( s1, s2 );
+
+        assertThat( result ).containsExactly( "1", "3", "5", "6" );
+    }
+
+    @Test
+    public void second_set_only()
+    {
+        Set<String> s1 = new HashSet<>();
+        s1.add( "1" );
+        s1.add( "2" );
+        s1.add( "3" );
+        s1.add( "4" );
+        s1.add( "5" );
+        Set<String> s2 = new HashSet<>();
+        s2.add( "3" );
+        s2.add( "5" );
+        Collection<String> result = Util.symmetricDifference( s1, s2 );
+
+        assertThat( result ).containsExactly( "1", "2", "4" );
+    }
+
+    @Test
+    public void list_with_duplicate()
+    {
+        List<String> s1 = new ArrayList<>();
+        s1.add( "1" );
+        s1.add( "2" );
+        s1.add( "2" );
+
+        Collection<String> result = Util.symmetricDifference( s1, new LinkedHashSet<>( s1 ) );
+
+        assertThat( result ).containsExactly( "2" );
+    }
+
+    @Test
+    public void list_with_tripple_entries()
+    {
+        List<String> s1 = new ArrayList<>();
+        s1.add( "1" );
+        s1.add( "2" );
+        s1.add( "2" );
+        s1.add( "2" );
+
+        Collection<String> result = Util.symmetricDifference( s1, new LinkedHashSet<>( s1 ) );
+
+        assertThat( result ).containsExactly( "2", "2" );
+    }
+}